1. Field of the Invention
The present invention refers to a printable recording material having an embedded image and to a process for manufacturing the same.
2. Description of the Related Art
Recently inkjet print processes have been developed in order to improve the quality of the resulting inkjet images so that photographic quality has been almost achieved. To fulfil these requirements inkjet recording materials have been developed having excellent printability especially definition of the inkjet printed image, high-gloss, improved scratch resistance and environmental resistance.
EP-A 0 732 219 and EP-A 0 634 283 refer to high-gloss recording materials made by a cast-coating process. High-gloss with simultaneous improved inkjet printability has been achieved by using pigments of extreme small particle size in the cast-coating.
EP-A 0 709 221 describes a high-gloss cast-coated paper having the additional inkjet receiving coating. This inkjet receiving coating is composed in order to maintain the high-gloss of the base paper combined with an improved ink absorption. These high-gloss cast-coated papers have the disadvantage that the inkjet image applied to these papers is exposed to the environment and therefore susceptible to photochemical, chemical and mechanical attack.
EP-A 992 359 discloses an ink jet paper comprising a substrate, a first ink receiving layer containing inorganic pigments and a binder and a second gloss providing surface layer.
To avoid this disadvantage it has been suggested in the past to cover the already printed recording material either by lamination or impregnation to make the printed image resistant with respect to any kind of environmental attack. Such lamination or impregnation processes are inter alia described in DE 3 610 204, EP-A 0 839 670, EP-A 0 343 794, U.S. Pat. No. 6,066,594 and DE-A 2 310 891. An important draw back of this technology is that an additional lamination or coating step after printing is involved which considerably increases the production costs.
This draw back can be avoided by inkjet recording materials that have a good initial inkjet printability combined with the possibility to change the surface morphology after the printing process. Such inkjet recording materials are known from EP-A 0826 823, DE-A 199 56 999 and EP-A 0 912 348. These inkjet recording materials have in common that they are coated with an inkjet receiving coating comprising as major component thermoplastic pigments. This gives the opportunity that the inkjet recording material after being printed can be subjected to elevated temperatures under pressure in order to fuse the individual thermoplastic pigments into a continuous thermoplastic film that protects the underlying inkjet image from environmental attack.
These inkjet recording materials as well as the prior art using lamination or impregnation to protect the inkjet image have the essential draw back that the surface of the inkjet recording material is sealed to an extend that the sheet is not any longer printable.
U.S. Pat. No. 3,889,270 discloses an ink jet recording material comprising an ink jet receiving layer formed by a molecular disperse or colloidal disperse substance in order to ensure wetting and penetration of the receiving layer by the ink. Embedding of the ink jet image is not described.
From WO 97/33758 an ink jet recording medium comprising a porous hydrophilic membrane and a continuous non-porous hygroscopic layer that may contain pigments in an unspecified amount. In one embodiment the recording medium can be post-treated after application of an ink jet image by for example calendering thereby collapsing the porous structure of the membrane to provide transparency. The purpose of the porous membrane is to ensure absorption of the solvents of the applied ink droplets, whereby the dyes and pigments of the ink still remain on the surface of the medium. Thus collapsing of the porous structure of the membrane does not result in an embedding of the applied ink jet image.
Thus, the object of the present invention is to avoid the disadvantage of the above-described prior art especially is to provide a recording material having already an image applied thereon whereby the gloss of the image is substantially the same as the gloss of the paper not covered by the image and the applied image is protected from environmental attack but at the same time the recording material still remains printable as well to provide a process to manufacture such a recording material.